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I have gone deep, deep down into the overheat rabbit hole.... If you hold down the settings symbol on Connext screen you can go do the diagnostics menu. Select the engine, and you can see if there are any codes. These relate directly to which sensor is the problem, sort of.
Diagnostic Code 15 with OBD-M code 52107 will be the engine temperature sensor (rear of engine)
Diagnostic Code 65 with OBD-M code 521022 will be the Exhaust manifold water temp sensor (called Thermo Sensor in the diagrams).
You can check these by just unplugging the sensors, they will pop the codes.
If you don't have a code (YDS-1) then it is going to be the Thermo Switch (the one at the front of the engine). It toom many trips to the dealer and showing them the service manual before they finally tested this switch and it was bad. It is a binary switch, so when it is out of spec it just doens't work right. You can unplug this switch and it will eventually trip the overheat, but the logic is not all clear to me. Best I can figure is that the computer is checking the position of the switch based on the temperature its reading on the temperature sensor. This switch is supposed to turn on between 201-212 degrees and turn off on the cool down between 201-176 degrees. However it works you just can't unplug it because it will still "overheat" and put you into limp mode. You can however unplug all three sensors and you will just have a check engine light, it will yell at you every time you start up, but you can run the engine no problem.
Anyway, they replaced it after it tested bad, and I didn't have problems for over about a year. Just thew a code on my last trip with the same symptoms. Instead of dealing with the dealer I just ordered the part and installed it. I guess they are having a lot of failures with these???
The problem with the Thermo Switch is that you have to remove the intake manifold to remove it. Trust me on this one, I have tried everything and the intake manifold physically blocks the bolt from coming out. If you don't want to deal with removing the intake manifold then make the dealer pull it and test it under warranty (if you have it). I didn't want to wait weeks on the dealer again in prime summer time so I just did this myself today. I guess I will see how long the new one lasts.
I had the feeling the it would be the Thermo Switch because I had unplugged the exhaust sensor and the thermosensor and it was still giving me "overheating" Alarms. the thermo switch was the next one I was going to troubleshoot and disconnect. I tried removing the thermo sensor without having to remove the manifold but it looks like it's inevitable. Man... thank you for all this information. I was going to call the dealership today to schedule a time to book me in but they're 8 hours away from me (573 miles one way). I wanted that option to be my last resort.
I had the feeling the it would be the Thermo Switch because I had unplugged the exhaust sensor and the thermosensor and it was still giving me "overheating" Alarms. the thermo switch was the next one I was going to troubleshoot and disconnect. I tried removing the thermo sensor without having to remove the manifold but it looks like it's inevitable. Man... thank you for all this information. I was going to call the dealership today to schedule a time to book me in but they're 8 hours away from me (573 miles one way). I wanted that option to be my last resort.
Probably not bad. For me it's just a hassle that i just bought my boat and to have these issues is just frustrating that's all. but definitely better than having to travel 8 hours to the dealer and back and doing it again to pick it up. I'm wondering if there's anyway I can have them file this as a claim on the warranty and reimburse me for the parts I replace. I don't know how that all works with a boat.
Probably not bad. For me it's just a hassle that i just bought my boat and to have these issues is just frustrating that's all. but definitely better than having to travel 8 hours to the dealer and back and doing it again to pick it up. I'm wondering if there's anyway I can have them file this as a claim on the warranty and reimburse me for the parts I replace. I don't know how that all works with a boat.
They're probably going to want a tech to do it. You might ask them to see if they'd have someone willing to meet you half way, or even to come to your house.
They're probably going to want a tech to do it. You might ask them to see if they'd have someone willing to meet you half way, or even to come to your house.
I've actually spoke to dealership owner who happens to be the main mechanic/technician. when I was picking up my boat, they were griping about traveling to Page, Arizona on 5 hour trip to and from. I can only imagine what they'll say coming to my house in NM which is a 8 hour trip one way lol.
Well, for me this time it was not the thermo switch.... took the boat out and it ran fine for about 2.5 hours. I was thinking that it was again the thermo switch but then it popped. Back to troubleshooting and trying to figure out which one is doing it. I did find this gem in the service manual though.
So in theory if the thermo switch is unplugged it can't trigger the overheat warning. I wish they would define "rises rapidly" and it is also good to know that the temperature sensor for the engine is good with anything under 248 degrees. I think I would notice something that hot with the IR temp gun. I am starting to think I have some sort of wiring problem or another sensor has gone bad. I did find that my wiring harness for all of these sensors has been rubbing on the exhaust of the starboard engine, I'm curious if anyone else has seen this??
